CT Only: Big Far Trader (Type R2)

[Grav_Moped]

As I believe already stated, not the same "ton".

Spacecraft hulls are specified in displacement tons of about 14 m³.

Vehicles are specified in metric tons (tonne) of 1000 kg.

A spacecraft would require about ten times as many "null grav modules" as you assumed.

Average starship density is 10 metric tons per Td? That's plausible, but is there a cite for that?

 

[AnotherDilbert]

The description (as with the one in '81) does not adjust performance for local gravity, indicating that discretionary thrust -- what's left over after weight neutralization -- is constant regardless of local gravity. Therefore, the non-discretionary thrust ("lift") must vary by local gravity. Striker grav drives work under a different paradigm.

By the same reasoning Traveller must have invented a new type of helicopter rotor whose thrust varies by local gravity. Note that there is no atmosphere requirement listed for helicopters, so the new type of rotors even works in vacuum. Yet we know that is not the case...


The short description in LBB3 is not a full and complete technical breakdown of how grav vehicles work. It is just a very short functional description of a vehicle. Of course there are more technical details...


Look at the LBB3 description of a Ground Car. Regardless of type, model, or make it has the same top speed, unaffected by, say, going uphill. So a current Ferrari and a Ford model T are just as fast, regardless of going up a steep hill or coming down. We know that is not the complete truth, but normally most cars are about as fast when driven more or less legally in traffic. A short paragraph can't list all the technical details determining the actual differences.

 

[AnotherDilbert]

Average starship density is 10 metric tons per Td? That's plausible, but is there a cite for that?

No rule, just a rough rule-of-thumb from MT and TNE where such things are specified.


Free Trader MT:

200 Dton, loaded mass 2280 tonnes.

Free trader TNE:

200 Dton, loaded mass 1908 tonnes.


Fat Trader TNE:

400 Dton, loaded mass 3906 tonnes.

 

[Grav_Moped]

By the same reasoning Traveller must have invented a new type of helicopter rotor whose thrust varies by local gravity. Note that there is no atmosphere requirement listed for helicopters, so the new type of rotors even works in vacuum. Yet we know that is not the case...


The short description in LBB3 is not a full and complete technical breakdown of how grav vehicles work. It is just a very short functional description of a vehicle. Of course there are more technical details...


Look at the LBB3 description of a Ground Car. Regardless of type, model, or make it has the same top speed, unaffected by, say, going uphill. So a current Ferrari and a Ford model T are just as fast, regardless of going up a steep hill or coming down. We know that is not the complete truth, but normally most cars are about as fast when driven more or less legally in traffic. A short paragraph can't list all the technical details determining the actual differences.

On the other hand, the air/raft description does indicate that it's affected by atmospheric conditions (cruise: 100kph, subject to wind effects; burst speed: 120kph).

They didn't need to detail the characteristics of helicopters or ground cars because the players already have a pretty good idea what those vehicles can do because they exist right now.

 

[Proneutron]

Average starship density is 10 metric tons per Td? That's plausible, but is there a cite for that?

Looking at a couple of MT 200 ton traders (unloaded) = 9.3 tons per Displacement ton. A vargr 100t scout came out to 12.8 per Dton, unloaded. Probably because not much empty cargo space...

 

[nobby-w]

IMTU ships normally rate at around ½G. This is because Trav (and every other game I've been able to peek into) assumes linear power requirement for acceleration. In truth, power is proportional to square of acceleration.

Change in kinetic energy is (although relative to a frame of reference), but the physics are more complex and don't work quite like that. If you're travelling at 2,000 m/sec and burn for 1,000m/sec dV you still use the same amount of reaction mass and energy going through the drive that you would if you started at 0 or 1,000 m/sec.

However, if you're travelling at 2,000 m/sec, the reaction mass starts out with kinetic energy appropriate to 2,000 m/sec rather than 1,000 so the same acceleration is imparting different amounts of kinetic energy.

The reason for this is all tied up in General Relativity. Kinetic energy exists with respect to a frame of reference (pretty much everything happens relative to a frame of reference - it's right there in the name). If you have two objects travelling at 1,000 m/sec almost parallel to each other, a collision will be rather a lot less energetic than the two objects colliding head on while going at 1,000m/sec in opposite directions, as the objects' velocity is different relative to each other even though they're both travelling at 1,000 m/sec.